In the major land battle of the Persian invasion in 480-479 BCE at Plataia in 479, the 5,000 Spartan warriors were part of the 38,700 heavy infantry of the southern Greek forces. With the auxiliary light troops the total force was 110,000.
The Persian army main force comprised 90,000 Persian troops plus about 40,000 central and northern Greek soldiers allied to them.
The southern Greek side won against the lightly armed Persians and their Greek allies in a battle where the southern Greeks avoided the superior Persian cavalry by staying on rough ground. Their superior armoured warriors broke the lighter armed Perians.
This was a lesson they had learned from the Athenian-Plataian force which won at Marathon ten years earlier – avoid the cavalry and the Persian infantry could not stand up to armoured infantry.